Techniques for improving Bulk Acoustic Wave (BAW) reflector and resonator structures are disclosed, including filters, oscillators and systems that may include such devices. A Bulk Acoustic Wave (BAW) resonator of this disclosure may comprise a substrate and an active piezoelectric resonant volume. The active piezoelectric resonant volume of the Bulk Acoustic Wave (BAW) resonator may have a main resonant frequency. The active piezoelectric resonant volume of the Bulk Acoustic Wave (BAW) resonator may comprise first and second piezoelectric layers having respective piezoelectric axis that substantially oppose one another. A first patterned layer may be disposed within the active piezoelectric volume. This may, but need not facilitate suppression of spurious modes. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in a super high frequency (SHF) band. The main resonant frequency of the Bulk Acoustic Wave (BAW) resonator may be in an extremely high frequency (EHF) band.

Disclosed is an acoustic resonator including a substrate including a first cavity, a first electrode formed above the substrate, a piezoelectric layer formed on one surface of the first electrode, and a second electrode formed on one surface of the piezoelectric layer. Here, the piezoelectric layer includes a longitudinal section not to cover a longitudinal section of the first electrode. Also, the second electrode covers the longitudinal section of the piezoelectric layer and extends to a first interpolar cavity which spaces the first electrode at least partially apart from the piezoelectric layer. A quality factor may be increased by fixing an increase in resistance which occurs due to thin film electrodes.

Provided is a method of manufacturing a bulk acoustic wave resonator, which includes: providing a piezoelectric substrate for forming a piezoelectric layer; forming a first electrode structure on the portion of the piezoelectric substrate for forming the piezoelectric layer; forming a dielectric layer on the first electrode structure, and performing a patterning process on the dielectric layer to form a patterned dielectric layer comprising a sacrificial dielectric part and a periphery dielectric part; forming a boundary layer on the patterned dielectric layer, the boundary layer covering a surface of the patterned dielectric layer and surrounding the sacrificial dielectric part; thinning the piezoelectric substrate to form the piezoelectric layer, the first electrode structure being located at a first side of the piezoelectric layer; forming a second electrode structure on a second side of the piezoelectric layer; and removing the sacrificial dielectric part to form a resonant cavity.

A method of forming a resonator structure can be provided by forming one or more template layers on a substrate, (a) epitaxially forming an AlScN layer on the template layer to a first thickness, (b) epitaxially forming an AlGaN interlayer on the AlScN layer to a second thickness that is substantially less than the first thickness, and repeating operations (a) and (b) until a total thickness of all AlScN layers and AlGaN interlayers provides a target thickness for a single crystal AlScN/AlGaN superlattice resonator structure on the template layer.

A method for forming a bulk acoustic wave resonance device, comprising: (S201) forming a first layer, which comprises: providing a first substrate; forming a piezoelectric layer located on the first substrate; forming a first electrode layer located on the piezoelectric layer; and forming a cavity pre-treatment layer located on the piezoelectric layer, used for forming a cavity, and at least covering a first end of the first electrode layer, wherein a first side of the first layer corresponds to the side of the first substrate; a second side of the first layer corresponds to the side of the cavity pre-treatment layer; (S203) forming a second layer, which comprises: providing a second substrate; (S205) connecting the first layer to the second layer, the second layer being located at the second side; (S207) removing the first substrate, so that the first side corresponds to the side of the piezoelectric layer; and (S209) forming a second electrode layer located at the first side and contacting with the piezoelectric layer. The formed piezoelectric layer does not comprise a crystal that is significantly turned so as to facilitate increasing the electromechanical coupling coefficient and the Q value of the resonance device. In addition, the second substrate processing and the active layer processing can be respectively performed, and are flexible.

A bulk acoustic wave resonator includes: a first electrode; a piezoelectric layer disposed on at least a portion of the first electrode; and a second electrode disposed on the piezoelectric layer. The piezoelectric layer contains a dopant, and a value of [a thickness (nm) of the piezoelectric layer×a concentration (at %) of the dopant]/100 is less than or equal to 80.

An acoustic wave device includes: a substrate; a first electrode on the substrate; a piezoelectric layer on the first electrode; and a second electrode on the piezoelectric layer. A bonding interface is located between the substrate and the first electrode. The full width at half maximum (FWHM) in the X-ray diffraction pattern of the crystal plane <002> of the piezoelectric layer is between 10 arc-sec and 3600 arc-sec.

A method of manufacturing a bulk acoustic wave filter is provided, including: forming an acoustic reflection air cavity, a sacrificial layer, a seed layer, a lower electrode layer and a piezoelectric layer of n resonators on a substrate in sequence, wherein n is greater than or equal to 2; taking N from 1 to n for respectively repeating following steps: forming an N-th metal hard mask layer, defining an effective area of a first resonator to an N-th resonator by using a photolithography process, removing the N-th metal hard mask layer outside the effective area of the first resonator to the N-th resonator, oxidizing the piezoelectric layer outside the effective area of the first resonator to the N-th resonator to form an N-th oxidized part of the piezoelectric layer, and etching the N-th oxidized part of the piezoelectric layer; removing the metal hard mask layer of the effective area of the first resonator to the N-th resonator, so as to form the piezoelectric layer having different thicknesses of the first resonator to the N-th resonator; and forming an upper electrode layer on the piezoelectric layer having different thicknesses of the first resonator to the N-th resonator.

A high Q acoustic BAW resonator with high coupling and improved spurious mode suppression is given. The BAW resonator comprises an active resonator region (AR) formed by an overlap of the three layers bottom electrode (BE), piezoelectric layer (PL) and top electrode layer (TE). An inner-flap (IF) is formed by a dielectric 3D structure sitting on a marginal region (MR) of the active resonator region (AR) or adjacent thereto, extending inwardly towards the center thereof and having a section that runs in parallel and distant to the top surface of the resonator keeping an inner gap (IG) thereto or an angle Θ.

A method of printing comprises providing a component source wafer comprising components, a transfer device, and a patterned substrate. The patterned substrate comprises substrate posts that extend from a surface of the patterned substrate. Components are picked up from the component source wafer by adhering the components to the transfer device. One or more of the picked-up components are printed to the patterned substrate by disposing each of the one or more picked-up components onto one of the substrate posts, thereby providing one or more printed components in a printed structure.